March 24, 2008

Study Offers Hope To Children With “˜Inoperable’ Kidney Tumors

by Sam Savage

Surgeons were able to save part of each kidney in patients with bilateral Wilms tumor, regardless of how the tumors appear on preoperative scans

Physicians at St. Jude Children's Research Hospital have demonstrated that children with bilateral Wilms tumor, a cancer of the kidneys, can retain normal function in both kidneys by undergoing a procedure called bilateral nephron-sparing surgery, even when preoperative scans suggest that the tumors are inoperable.

Between 1999 and 2006, all St. Jude patients with bilateral Wilms tumor exhibiting favorable histology (cell characteristics) underwent bilateral nephron-sparing surgeries, or partial nephrectomies. Nephron-sparing surgery is designed to remove the malignant tumor, sparing as much healthy kidney tissue as possible. In all 10 instances where the procedure was used, the surgery was successful, often despite preoperative imaging studies suggesting that kidney preservation might not be possible.

"Many times, physicians will look at a child's scans and assume that it is impossible to remove the tumor while preserving some uninvolved kidney, but our study indicates that surgeons should not rely solely on the imaging to make that decision," said Andrew Davidoff, M.D., division chief of General Pediatric Surgery at St. Jude and the senior author of a retrospective study that appears in the advance online publication of the journal "Cancer."

Traditionally, patients with bilateral Wilms tumor have one"”and sometimes both"”kidneys removed in an attempt to eradicate the cancer. If one kidney is removed and the cancer recurs in the other kidney, the possibility of losing renal function is high. If both kidneys are removed, the child must endure dialysis and a possible kidney transplant.

"In most cases, the surgeon will be able to save normal kidney on both sides," Davidoff said. "The study indicates that, when combined with chemotherapy and radiation therapy, this surgical approach provides an opportunity to preserve renal function while maintaining a high probability of cure."

Wilms tumor is the third most common solid tumor in children, with approximately 500 cases diagnosed each year in the United States. Only 5 to 7 percent of those patients will have tumors in both kidneys. Because children with bilateral disease are at risk for developing renal failure, physicians must balance a desire to maintain long-term renal function with the goal of eliminating the cancer.

Since 1999, St. Jude patients whose bilateral Wilms tumor exhibits favorable histology have received chemotherapy, consisting of vincristine, dactinomycin and doxorubicin, followed by bilateral partial nephrectomies within 12 weeks of initiation of chemotherapy. Patients in the retrospective study ranged in age from 5 months to 9 years old and were generally referred to St. Jude because of poor response to therapy or unfavorable anatomy. Many of the children received radiation after undergoing surgery.

According to Davidoff, nephron-sparing surgery is a more complex procedure than a complete nephrectomy. "Commonly, when a child has bilateral disease, the surgeon will remove the kidney that has the most tumor and do a partial nephrectomy on the other side," he said. "But if a patient then develops problems in the remaining kidney, the options are limited because one kidney has been taken out of the equation. At St. Jude, we try to save as much kidney as possible in children with bilateral disease. Thus far, 100 percent of the time we have been able to save normal kidney on both sides."

All patients who exhibited favorable histology Wilms tumor are still alive, a mean of nearly four years after initial surgery. Nine of the patients exhibited normal renal function at their most recent follow-up exams.

Other authors of this paper include Jesse J. Jenkins and Matthew J. Krasin (St. Jude); Mark A. Williams and Deborah P. Jones (St. Jude and University of Tennessee, Memphis); Dana W. Giel (University of Tennessee, Memphis); Fredric A. Hoffer (University of Washington, formerly of St. Jude); and Jeffrey S. Dome (Children's National Medical Center, formerly of St. Jude and the University of Tennessee, Memphis).

This work was supported by a U.S. Public Health Service Childhood Solid Tumor Program grant, a Cancer Center Support Grant from the National Cancer Institute and ALSAC.